Heretofore, such as shown in U.S. Pat. No. 4,920,626 dated May 1, 1990, apparatus has been provided for mounting an instrument manifold on a main flow line for transmitting radially directed forces between the instrument manifold and an orifice plate assembly or fitting on the main flow line. The mounting apparatus includes a pair of generally identical stabilized connector subassemblies connected between the instrument manifold and the orifice plate assembly with one connector subassembly being connected to a high pressure fluid port on the upstream side of the orifice plate and the other connector subassembly being connected to a low pressure fluid port on the downstream side of the orifice plate. Each connector subassembly comprises a connector body having an inner externally threaded end for threading within an associated fluid port on the orifice assembly and an outer flange for connection to a mating flange on the instrument manifold. The tapered threads on the inner end of the connector body form a fluid tight metal-to-metal seal with the associated fluid port and leakage may occur if such threads crack or are loosened such as might result from radial forces exerted against the connector body and continuous deflection of the connector body from such radial loads or forces.
The stabilized connector shown in U.S. Pat. No. 4,920,626 transmits radial forces from the manifold to an outer end portion of the connector body, and then from the outer end portion to a tensioning nut for transmitting the radial forces to the surface of the orifice assembly at a position radially spaced from the threaded inner end of the connector body thereby to minimize or prevent radial forces from being transmitted through the threaded inner end of the connector body to the orifice assembly. The weight of the manifold and equipment connected thereto, such as fluid pressure transmitters, exerts a static radial load on the stabilized connector. Dynamic radial loads such as provided by vibrations, seismic activity, or exerted by workmen or the like contacting the manifold or associated equipment, may be exerted by the stabilizer connector. A stress concentration resulting from the bending moment generated by the radial loads occurs in the connector body immediately adjacent the tensioning nut. Under prolonged periods of use, particularly when continuous vibrations occur from fluid flow or thermal cycling in the associated main flow line, fatigue may occur in the connector body at the tensioning nut. Also, loosening of the tensioning nut may occur from such use and possible elongation of the connector body from the compressive force exerted by the tensioning nut against the orifice fitting assembly.
Further, when the stabilized connector shown in the aforesaid patent transmits radial loads from the manifold to an arcuate surface of the orifice plate assembly, the stabilizer member contacts the arcuate surface along a line contact area at a location spaced substantially from the threaded end of the connector body thereby to provide a relatively high unit stress thereat.